Art of distillation of petroleum oils



Sept. 24, 1929. R. w. HANNA ART OF DISTILLATION OF PETROLEUM OILS.

` 3 Sheets-Sheet 2 Filed oct. 4, 1925 Sept. 24, 1929. R, w, HANNA ART 0F bIsTILLATIoN 0F PETROLEUH oILs Filed Oct; 4, 1923 3 Sheets-Sheet 3 R) iii D@ m.

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'Patented Sept. 24, 1929 UNiTED STATESA PATENT-' OFFICE l, RICHARD W. IIANNAJ or RIEDMONT, CALIFORNIA, AssIGNoR, RY MnsNE AssIGN- MENTS, 'ro s'rANDARD OIL COMPANY or cALIzrORNIA, OF sAN FRANCISCO, CALL RoRNIA, A CORPORATION OF DELAWARE l .ART F DISTILLATION 0F PETROLEUM ILS Application filed October 4, 1923. `Serial No. 666,474. v

This invention relates to the art of petro-v leum distillation. 'It has to do particularly with a distillation method by which a num-V ber of different and desired fractions are produced from a base stock and is of particular use in the vacuum distillation of lubricating oil stocks. 1

In certain petroleum distillation operations it is desirable to separate the distillate 0 obtained from base (petroleum) stocks into a number of different fractions'or cuts pos- ,sessing different'ranges of boiling points with corresponding ranges 1n viscosity,

gravity, and other characteristics. Such aI 5 separation of various fractions is desirable in ther. production of lubricating oils Where the different grades may range from the wherein the different cuts or fractions have been thrown over by holding the distilling o unit at successively increasing stages of teniperatureor to employ a continuous operation ivitli a number of distilling units arranged in a. series and each succeeding unit of the series held at a progressively 'iii- 5 creasing temperature. In either case the" different boiling-point fractions are removed in the order of their vaporizing temperaturcs. l

In producing a number of. different cuts or fractions of lubricating oil stock, difficulty is encountered by the presence, in the base stock from which the lubricating oil fractions are obtained, of light fractions which have not been entirely removed during the topping operations which take place prior to the removal from the crude petroleum of the lubricating' oil fractions. There may also be present7 in the stock from which the lubricatingoils are distilled, the so-called gas oil cut. Still other light and relatively lowboiling-point constituents are generally p resent in the lubricating oil stock being distilled, due to the slight cracking which takes place at the temperatures necessary for lubrioating'v oil distillation. All of these light 55 and lovv-boiling-point constituents serve to contaminate the lubricating. oil cuts produced, so that when the requiredl viscosity for a particular fraction is reached, 'the corresponding fiash point is too low. As a re` sult of this low flash points it becomes necessary to subject the resulting lubricating oil fraction to a reducing distillation step.

Some degree'of success has been encoun tered In y overcoming this low-tlashpoint 65 trouble and in eliminating the necessity for reducing operations by employing fractional condensation equipment during the continuous distillation of lubricating oil stock. This fractional condensation equipment has been of the usual type long known to the art and the success of such operation has been not so much in the use of the fractional condensing equipment as in the fact that a relatively large number ofdistilling units arranged in a series have been used and substantially all of the gas oil and other light fractions removed in the lirst'units of the series and Abefore the oil reaches those units where the desired lubricating oil cuts Aare taken off. l i

Ina distillation operation for the production of lubricating oil fractions, if, instead of employing a number of distilling units operated-in series wherein the desired higher-boiling-point oils are vaporized separately, the entire composite lubricating Oil stock, comprising the light, as Well as the heavy constituents, be fed into a single distilling unit operated .continuously and at a uniform or constant temperature, certain advantageous results from the distilling standpoint are obtained. It has been found that by such a distilling operation wherein the vapors`froin the higher boiling-point oils are evolved simultaneously and in a commingled state with the vapors of the loWer-boilingpoint oils, the temperature at Which the higher boiling-point oils can be vaporized is materially reduced. When such distillation is conducted continuously, and at a greatly reduced pressure and preferably with the use from each other of the different grades of of steam, and the highestboiling-point oils vaporized simultaneously With the vaporization of a vmaterial quantity of substantially lower-boiling-point oils, the temperature at which the highest-'boiling-point oils may be vapor-ized is so reduced that decomposition of such oils by cracking .is substantially prevented and a material increase in the productionof the desiredv high-boiling-point and high-viscosity lubricating oil .fractions made possible.

lVhen these advantageous results are thus obtained, it Will be evident that, due to the vapors of the high-boiling-point vand lowboiling-point oils being evolved simultane ously and in a commingled state, subsequent separation of those loiv-boilingpoint oils which lower theflash-point of the-desired lubricating oils, together With' a separation lubricating oil cuts, becomes necessary. vTo

.merely condense these combined vapors Without separation would be to produce a condensate unsuitable for treating and tinishing as a lubricating oil. A

The objects of this invention are to provide for aA continuous distillation of the oil to be treated in a single unit under a reduced pressure less than atmospheric, (either with or Without steam,) and at a substantially uniform and constant temperature,

the vapors of the loWer-boiling-point oils being vaporized simultaneously with the v vaporization of the higher-boiling-point oils,

l fractional condensation connection With a description ofa process' comprising a preferred embodiment of the invention and by reference to theaccompanying drawings which illustrate-an apparatus in which may be performed a proc` ess comprising a preferred embodiment of my invention. The indicated'apparatus is given for illustrative purposes only, and it is to be understood that the arrangement shovvn and the details of construction illustrated may be Widely varied Without departing from the scope of my invention.

In the drawings:

In Fig. .l I have indicated an apparatus by means of which a process embodying my invention may be performed. In the ap paratus as described in this figure, I have illust-rated means for pre-heating the oil to be heated so as to materially increase the rate of evolution of the commingled vapors, giving an increased yield for the same charging rate'or for the same yield, permitting an increased charging rate.

In Fig. 2 I have illustrated an apparatus of simpler form omitting the step of high pre-heating of the oil to be treated before its introduction into the vaporizing still.

F ig. 3 illustrates a form of fractionating condenser which may be employed.

Fig. 4- illustrates a re-heating fractional condenser which may bel employed as a part of the apparatus. I

Referring to Fig. l:

2 represent-s a storage tank orl source of supply. 3 represents the feed-line of the system in which is a suitable pump 4 for supplying the oil to be distilled through thefeed-line 3 under suitable pressure and by which the desired velocity of 'flow is maintained. The feed-line 3 passes through a vapor heat exchanger 5, of ordinary or any preferred construction, and thence passes -through a residuum 'heat exchanger 6, of

ordinary or any preferred construction, and thence through the heating coil 7. This heating coil is mounted in a suitable furnace t5 and heated bv suitable means, such as for example a burner 9. From this heating coil 7 l the heated oil passes to a still or vaporizing chamber 10. In line between the coil and' the outlet into the vaporizing chamber 10, I interpose a suitable pressure controlling valve 12, which may be set to maintain such pressure as may be desired or required. The form, shape or design'of the still or evaporating chamber 10 may be varied as desired, and its form or shape or construction forms no part of the present invention. As shown,

this still or evaporator 10 is mounted over a lsuitable furnace 13 provided .With heating means, such as a burner 14. In practice, the evaporator may be heat-insulated to prevent radiation losses, represents the vapor outlet line Which passes from the evapora-` tor 10 through the vapor heat exchanger 5 and thence to the inlet chamber of the reheating 'fractional condenser 3l. From this inlet chamber 30 the vapors pass through the tubes 32 into the outlet chamber and thence by the pipe 34 to a second fractional condenser 35.v This fractional condenserl 35 maybe of the form and construction illustrated in Fig. 3. After circulating lthrough the chamber of the condenser 35,

the uncondensed vapors pass through the' outlet pipey 36 and into a second fractional condenser 37. This fractional condenser 37 Amay be of the ordinary or any-preferred construction, such for instance as the frac- A tional condenser of Fig. 3. l38 represents the'vapor outlet pipefrom the fractional condenser- 37. This outlet pipe 'leads into the condensing chamber 39,0f the re-heating fractional condenser 31, above the upper pipe or tube 32. Within this chamber 39 are `mounted a series of pans 40 preferably circupans 40. The rising vapors fromthe inlet pipe 38 are thus caused to pass through a' curtain of descending condensate dropping from the` lower partition 41 to the lower pan 40 and through successive curtains of de-l scending condensate in passing around successive pans and up through the openings in successive partitions 41 and into thevaporline 42. This vapor-line 42 is connected with a final fractional condenser 43, from which condenser the lightest distillate produced is withdrawn. 44-indicates the pipe or line byv which 'the `said distillate is Withdrawn from thev condenser 43. This pipe-or conduit 44 is connected to a suitable storagetak (not shown) passing first thrbugh s itable cooling coil 45 see Fig. 2) in a sui able cooler 46..and thence through lock-boxes 47 anda receiving drum 48. Thig receiving drum is connectedA by a suitable line witha distillate storage tank E, a suitable suction-pump 49 being interposed in this line. The receiving drum 48 is connected by a suitable line. 21 with the vacuum pump 20. 22 (Fig. 2) represents the exhaust from the vacuum pump. As tliislatter and' apparatus and connections as shown in Fig. 2 may be readily connected to andused in the apparatus indicated in Fig. 1, I have not deemed it necessary to` extend and show the same in Fig. 1. 50, 51, 52 indicate respectively the conduitspor lines leading from the lower portions of the condensing chambers of the condensers 37, 35.. 31, respectively. These respective conduit lines50. 51, 52 are connected (as indicated in Fig. 2) through suitable cooling` coils in coolers 46 and thence through suitable lock-boxes 47 to receiving drums 48 and thence to distillate storage tanks or drums C, B, l), respectively. Each ofthe rey ceiving drums is connected with the vacuum pump 20. 53 represents a condensate line leading from the chamber 33 of the condenser 31 and is in turn connected through a suitable .cooling coil 45 in a 4cooler 46, through a suitable lock-boX 47 and to a suitable receiving drum 17 and thence through a, distillate pump and line to a distillate storage tank 54 represents a cooling medium supplying conduit connected with a. suitable source of supply (not shown). This cooling medium is preferably water. As indicated in both Fig. 1 and Fig. 2, the direct ,line of this conduit 54 is through the Valve 55, coil 56 in the chamber 39 of the re-heating fractional condenser 31, and thence back to discharge. A branch line 57 leads through a valve 58 into the' condenser 43, passingdownward through the"v tubes .or pipes 59 thereof` and out through the conduit 6() into the return leg ofthe line 54. 61 represents a valve in this line. Theinlet portion of the'line 54 is connected just beyond thebranch 57 with a branch line 62 which communicates into the discharge conduit 60 below the condenser 43. 63 represents a suitable valve in-this line. From the feedline 3 leads a branch pipe 64, by means of which the relatively cool oil to be treated may be used as a cooling medium' for the condensers 35, 37. By using such feed-oil as a coolingmedium in such condensing operation, heat economy is effected and the feedoil after passing through the condenser 37 and thence the condenser 35, is returned to the line 3, atraised temperature, by the return leg of such conduit. 66 and 67 represent suitable valves controlling this conduit. The branch conduit 64 is connected directly withthe condenser 37, and the feed-oil, after passing downward through the tubes there'- of, passes into thel return leg 65 through the pipe 68. A branch 69 leads from, the line 64 to the condenser 35, and the condenser 35 is connected at its lbottom by a pipe 70 with the return leg 65. 71 represents a branch ipe or conduit connected with the line 64 between the branch 69 thereof and the condenser 37. This branch line 71 is connected with the outlet-line 68 of the condenser 37.

72, 73, 74, 75, 76 and 77 indicate suitablel valves by which the flow of cooling medium through this cooling 'system may be controlled and regulated as desired. 78 indicates a valve interposed in the line 3 between the branch 64`and thereturn leg 65 thereofso that by suitable regulation of the valves into the still or evaporating chamber 10, the end 28 of such steam-line being preferably in the form of a perforated pipe located near the bottom ofthe evaporating chamber. 29 indicates a valve controlling such steam.- line. The steam-line 27 is connected to a suitable source of steam supply (notshown) storage 26. llf desired, the oil to be treatedl may be discharged into a suitable evaporat- Fig. 1, except that thea parat-us and connections for high iire pi'eieatingl-of the feedoil are o mitted. I have, therefore, in these tivo figures of the drawings used the same reference numerals as indicating corresponding parts. In F ig.' 2 the oil-cooling and preheating branch line 64 is shown as provided r"with a branch-linev79 connecting to the feedline 3 beyond the residuum heat exchanger 6, and the ret-urn leg 65 is shown as pro- 'vided With a branch line 80 connected with the feed-line 3 beyond the residuum heat 'exchanger 6. A valve 8l is interposed in the 'feed-line 3 between the connections of the lilies 79 and 80 therewith, and the lines 79 and 80are respectively provided with valves 82, 83. The oil to be treated, after passing through the feed-lineand residuum heat exchanger 6, may by means of regulation of the valves 8 1, l82,4 83, be passed into the cooling 'branch line 64 and back into the line 3 by the 'return leg A8.0, 'thus utilizing the partially heated oil when so'desired.

In the preferredembodiment of myv in- .-i'entioin a process of dist-illing the composite basic stock containing all the different lubricating oil fractions to produce lubricating distillates ready for treating and iin- .Sishing as lhbricat-ing oils, the first step is the preheating of suchstock to betreated `to a i'ni'i'cli higher degree than can economicallyv be obtained bythe use of heat exchangers .by which-the Wasteheat of the system is 'uti'lized, i. e. at temperatures below 400o F. k"I have found that'a material Aincrease in ythe rate of evolution of the cominingled vapors from this composite stock is obtained, `l`giving an increased yield for the same charg- `ing rate or for the same yield, permitting an increased charging rate, when the stock fed into the distilling chamber is pre-heatedto temperatures higher thancan economically 'be obtained by the use of such Waste -heat vexchangers,'i. e.: when such stock is heated to above A-LOO" F. `This pre-heating of such Astock may be extended up to 800 F., and is conducted at pressures higher than those un- 'der Which distillation takesl place, after which the heated oil may be injected into a Vaporizing chamber held at pressures less than atmos- `pheric'. This pre-lieating may or may'iiot 'be carried on in the presence of steam or `Water' vapor, the vaporizing cliamber may or may'not be supplied With additional heat therefore, pass the body of oil to be distilled through the heating element 7 in relatively vsmall streams and maintain as high a veloc- 'ityf of the -oil passing Jtherethrough as is consistent.' with the heat transfer from such heat-ing elementto the oil and the mechanical' conditions and adaptations of the partic- -ular apparatus and discharge the heated oil intoA the vaporizing chamber as quickly as possible after it has been raised to such temp eiatiiie. I maintain such a pressure of thev cvolved'vapors inthe heating coil and conduit to the vaporizing chamber as may be required .under the conditions of operation to substantially maintain the oil as it is being heated, and whenheated, substantially allin .liquid phase. Vaporization of such heated oil is effected in asingle' vaporizing chamber vunder a reduced pressure less than atmospheric. Under certain conditions of operation I have distilled oil iii accordance with my process with as high as 26 inches of vacuum inthe vaporizing chamber.

In a modification of my preferred process, the oil, instead of being heated'in the heating eleineiit'to the highest degree of temperature utilized in the distilling operation, may be heated only approximately thereto and a reasonable rise in temperature of the body ot the oil effected in the vaporizing chamber by v the application of exterior heat, as by means of a burner 14., and either `with or Without the use of steam, therein., IIoWever, in such a modification and embodiment of my invention, the body of'oil heated in the heating element is lraised to such a temperature that it may be brought to the lhighest temperature of the distilling operation Without the 'necessity of such a heat transfer in the evap- -orating chamber as Will cause material cracking of any portions of the oil therein.

'Where in the heating element 7 the temperature of the oil to be distilled is raised above 'the cracking temperature of portions there-- of, the oil being maintained substantially all in liquid phase`V therein by maintaining suitable pressure thereon, the oil is quickly discharged, after reaching thedesired temperatuie, into fthe vacuum vaporizing chamber 10 so that the heated oilis not subjected to such cracking temperature for a `sufficient time mand upon the shell of theevaporating chamber is not Y sutlicient to cause substantial cracking of portions of the oil undergoing distillation. Vith such fired pre-heatingof the oil, where using certain California oils, I have Ifound by raisinglsuch oil in the heating element to the temperature of 750-800 F.; and retaining the same in liquid phase, immediately injecting such heated oil into a vaporizipg chamber under vacuum, vaporization of the desired fractions of the oil takes place without cracking sired to vaporizc a higher-boiling-point or more viscous fraction of fractions, some .additional heating may be required in the. vapory izing chamber. Vithout such additional heat supply in the vaporizing chamber, the resultant liquid oil may be maintained therein at substantially 630 F. Temperatures even above 630 F. have been thus attained in the liquid body in such vaporizing chamber. If

only the heat lost by radiation is supplied to the vaporizing chamber, this temperature ofthe oil iii-the vaporizing chamber is held uniform, i. e., there is no differential temperature between the body of such oil and the shell of lthe vaporizing chamber. Furthermore, by applying additional heat to the vaporizing chamber in any degree less than sufficient to cause cracking or decomposition at the contact between the shell of the vaporizing chamber and the oil therein, a still higher temperature may be maintained in such oil body. By thus delivering'the oil to be distilled into the vaporizing chamber at such increased temperature, I am able toA attain a marked increase in the charging rate and, therefore, an increased capacity for the production of highboiling-point. and high-viscosityoils. Also high-boiling-point and high-viscosity oil from a given stock. In certain runs the rate of charging must be properly proportioned to permit the vaporization of such higheri Jooiling-point and higher-viscosity oil. The lubricating oil Athus produced is of a marked superior quality. Aside from having a high boiling point and a higher viscosity, dueto l higher tempera-tures and deeper cuts employed, I produce a higher-viscosity oil due f to the absence of cracking compoundsv A 'better color is also maintained and the treating loss will beefound to be reduced.

If,however,' it be not .desired to utilize this feature of high-fired pre-heat and maintaining the oil in liquid phase bypressure during such pre-heat and the immediate discharge of the highly pre-heated oilinto the vacuum chamber before cracking takes place, I have found that the oilcan be subj ected to La progressively increasing heat, ma-

terially higher than that obtained by the use lof waste heat exchangers,` but to a lower temperature than that obtainable inthe heating element 7 as heretoforesetv forth. For

If, however, it is de- I am able to cut deeper and produce more example, utilizationof the waste heat of the operation `cannot economically be utilized to v y raise the oil to be distilled to above 400 F.

- Additional heat may be supplied to the oil by 'means of the heating element 7 to raise thetemperature thereof to any desired degree below the cracking temperature of any appreciable portion thereof, and if such tem-A peratureis' not sufficient or the Vaporiza- ,tion of the desired high-boiling-point, highl viscosity fractions desired to be distilled, the

required additional heat can then be supplied in the vaporizing chamber without, danger of cracking,7 inasmuch as the temperature lof the oil has been raised to such an approximation of the temperature of the desii-ed distilling operation that the heat differential between the body of oil to be distilled as injected into suchf vapo-rizing chamber and the' shell temperature required for the required heat transfer from the vaporizer 10 tion at a higher temperature without cracking" than has heretofore been possible. Increased capacity, increased charging rate, or deeper cut, is thus rendered possible.

It is obvious that this highly pre-heated oil may be injected into the vacuum Vaporizing chamber' either above or into the liquid therein. If desired, such oil may be injected onto a spreading-pan, as indicated at 11 in the drawings, or other spreading or distributing means. l

- From the foregoing it is seen that this step of high-fired pre-heating of the stock to be distilled comprehends in its several aspects the continuous distillation at a pressure below atmospheric, by first heating such oil to be distilled at a pressure higher than that under which distillation takes place,

4such heating being effected either with or 'without the presence of water' vapors or steam and to a temperature higher than can be economically obtained by the use of heat exchangers utilizing the wastejheat of the system, i. e.; to temperatures between 400 F. and 800"F.,"injecting such heated oil into a chamber-'maintained at a pressure less than atmospheric, which chamber may or may not be supplied with addi-tional heat, depending upon the degree to which the oil has been heated .before interjection therein, and in which chamber additional steam may or may 'not be injected, as preferred,'the manner of injecting the highly heatedoil into the vacuum vaporizing chamber being preferably above the surface of the liquid therein in such a manner as to expose ythe maximum vapori-"= zation surface to facilitate-distillation, al-

" though if desired such injection may be beratively higher-boiling-pointA fractions than would be vaporized at the given temperatures Were such higherboiling^point fractions vaporized alone after the vaporization of such relatively lower-boiling-point fractions. All of such vapors are-Withdrawn from the va` porizing chamber intermingled and 'pass to the condensing apparatus.

The next step of my invention is to. sep-A arate and segregate the intermingled relatively lower-boilingpoint and relatively higher-boilingpoint oils contained lin the indistillin-g operation through the steps of condensation and segregation. The highly heatcd vapors first pass intothe chamber 30 of the re-heating fractional condenser 3l and pass through thel tubes 32 thereof into the chamber 33. The descendingcondensate from the upper chamber 39 contacts with the tubes 32 highly heated by the passage' of the vapors therethrough, and this' condensate or reflux is thus rc-hcated and those light fractions which are low in flash-point are revaporized and the resulting condensate from which they are separated is withdrawn through the pipe or conduit 52 to the distillate storage tank 'D The effect of this. heat transfer is tocause a certain condensation of the highesthboilingpoint vapors in the chamber 33. This condensate is drawn off from the vchamber 33 by the pipe'53 to the storage tank A. The vapors passing from the. chamber 33 through the conduit 34 and into the condenser 35 are further cooled therein and the condensate forming therein is withdrawn through the pipe 5l to the distillate storage tank B. The vapors passing from the condenser 35 through the -pipe 36 to'thecondenser 37 arc further contermingledvapors Withdrawn -from the vas densed in the latter and the condensate thereporizing; chamber. It -is highly advantageous .to effect this'separation in such manner and under such conditions that the produced condensates will be distillates of the desired boiling points and viscosities and not require rerunning or reducing to provide a stock Areadyfor treating and fnishinguas lubricating oil; also .to remove from the respective distillates thoselighter and 'lower-boiling point constituents which serve to contaminate the distillates produced by lowering the HashpointV thereof.

In the preferred embodiment of a process embodying my invention, therefore, I prefer to utilize the highlieat of the intermingled vapors as Withdrawn from the vaporizing chamber as a means for re-heating the condensate of the relatively loWer-boiling-point oils. I,` therefore, pass these intermingled. vapors through closed conduits contained Within .a chamber, to which chamber is returned the vapors of the lighter or lower-boiling-point fractions, said returned vapors being brought vto a lower temperature by a controllable cooling means located within said chamber whereby a reflux results from said lreturned vapors, and re-heatingy this reflux through the means of the heat of the total, intel-mingled evolved vapors passing from the evaporating chamber or still through said passages of said chamber, thereby revaporizing and separating from such refiux those light fractions which are lovv in flash-point. This step of the process may be more readily understood in connection With the detailed explanation of such preferred embodiment. I will, therefore, trace the course of passage of the Withdrawn intermingled vapors of the in formed drawn by the pipe into'the distillate storage tank C. The vapors ascending from this condenser 37 pass by the vapor con duit 3S into the chamber -39 of the re-hcating fractional condenser 3l,Wherein they are partially condensed, the condensate subjected f to re-heatinfr as before described, and the vapors pass out through the vapor-line 42 and into the final condenser 43, the'conden 'sate of which is drawn by the pipe 44 into the storage tank E. From the foregoing description, it will 'readily be seen that by this controllable fractional condensation of the intermingled vapors of distillation I am able to produce distillates of the desired boiling point range substantially free from low-flashpoint oil, and `that each of-these distillates is completely distilled and forms an oil ready for. treatment and-.finishing as a lubricating oil. Re-runningor reducing is obviated.

Whilein the, preferred 4process forming a tpreferred embodiment of my invention I prefer to utilize Vthe relatively cold fresh feed of the oil to .be distilled as the coolingmedium for the condensers,. (such as condcnsers 35, 37,) of the intermediate distillates, and to use Water circulation as the cooling medium for controlled vregulation of the condensation in the initial or final condensers, it is obvious that any controllable cooling medium may be used for these purposes, and the invention is l. The process of separating petroleum"y vapors, which comprises passing such vapors at al temperature below that at Which por vll( tions of'the vapors would crack or decompose through closed passages contained within a chamber, thence through chambers held at successively lowered temperatures and in which condensates of' successively lower boiling points are condensed from the vapors, separately withdrawing such condensates, returning the residue vapors from these chambers to.; the first mentioned-chamber,wherein" reflux of the heavier -fractions of the returned vapors is obtained by a cooling means and in which chamber `this reflux is reheated and partially revaporized by heat lsupplied by the total .and initial vapors, withdrawing the residue V ,reflux remaining froinsaid revaporization,

and-separately withdrawing the condensate which `forms'in the closed 'vapor passages through which the total and initial vapors PeSS- 2. The process of the separation of petroleum vapors, which comprises passing Ithe `vz'iporsata'temperature `below that at which portions thereof would crack or decompose through closed passages contained Within a.

chamber, thence through chambers held atl .successively lower temperatures and in which condensates of successively lower boiling points are. condensed `from the vapors,l separately withdrawing saidl con-- densates, returning the residue vapors' from these ychambers to the first `men-- tioned chamberl wherein these vapors are brought to a lower temperature by controllablecooling means, thus producing a reflux. ofthe higher boiling point constituents of the returned vapors, subjecting such reflux to a higher temperature through lthe means of the total and initial vapors, withdrawing the residue reflux remaining 'from said revaporization, and separately withdrawing the condensate which forms in the closed vaporpassages through which the total and initial vapors pass.

3. A process of separating mixed petroleum vapors, Vwhich includes passing all of such vapors, ata temperature below that -at which portions thereofv wouldA crack or decompose, through closed transverse passages contained within a chamber, Withdrawing and returning a part of said vapors to said chamber, wherein reflux of the heavier yfractions of the'returned vapors is ob tained by-a -cooling means, and in which chamber this reflux is reheatedand partially Arevaporized by heat supplied by the first said petroleum 'vapors but outvof'i'cont'act therewith, and withdrawing-the' residue reflux remaining from said revaporization.

'4. A process of separating. mixed petroleum vapors, which includes passing'such vav pors at a temperature below that at whichI portions thereof would crack or decom se through closed transverse passages contained within a chamber, withdrawing and returningv a part of said vapors to said chamber, wherein reflux of the heavier fractions of the returned vapors is obtained by a cooling means, and in which Ichamber this reflux is reheated and partially revaporized by heat.V supplied bythe first said petroleum vapors but out of contact therewith, and withdrawing the residue reflux and'separately withdrawing the condensate which forms in the closed vapor passages through which the total vapors pass.

5. A process of separating petroleum vapors,'which comprises passing suoli vapors at a temperature below that at which prtions of thevapors would crack or decompose through closed passages contained within a reflux condenser chamber in which passages partial condensation takes place, withdrawing the condensate `formed during `the passage, 'of said vvapors through said .closed passages, subjecting the remaining vapors to partial condensation in 'a separate chamber from which the condensate is withdrawn, returning the uncondensed vapors therefrom to said reflux- 'condenser chamber lwherein such vapors are subjected to further `refiuxcondensation and the reflux obtained thereby is relieated and the low boiling point constituents of vsuch reflux revaporized by the heat vsupplied by the passage` therevthrough of the original vapors, withdrawing 

